Test apparatus for testing integrated modules and method for operating a test apparatus

ABSTRACT

A test apparatus for testing integrated modules has a plurality of connection locations on a carrier substrate. An integrated module may be connected, via a connection location, to a test unit connected to the carrier substrate. The connection locations are arranged in groups within a connection array. A control terminal via which an integrated module may be selected for a test can be provided for each connection location. An address and command terminal can be provided for each connection location. The modules of the number of groups, which are simultaneously operated, are connected to the address and command bus via the respective switching means or switch. The test frequency can thus be increased without adversely affecting the driver load.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority under 35 USC § 119 to GermanApplication No. 10310140.3, filed on Mar. 7, 2003, and titled “TestApparatus for Testing Integrated Modules and Method for Operating a TestApparatus,” the entire contents of which are hereby incorporated byreference.

FIELD OF THE INVENTION

[0002] The present invention relates to a test apparatus for testingintegrated modules having a carrier substrate and to a method foroperating a test apparatus of this type.

BACKGROUND

[0003] In order to keep the failure rate of integrated modules as low aspossible following the fabrication thereof, the manufacturer subjectsintegrated modules such as, for example, DRAM memories to a burn-in test(or stress test), in particular, in which the modules are artificiallyaged. A burn-in test of this type is intended to sort out thoseintegrated modules, which fail after a short operating time, so that theuser receives modules which attain a defined service life.

[0004] In order to artificially age an integrated module, a relativelyhigh voltage, in particular, is applied to the latter in the burn-intest, said voltage causing the module to artificially age relativelyquickly, with the result that the ageing process is accelerated in arelatively small amount of elapsed test time. In addition or as analternative, the modules are exposed to an elevated ambient temperature,thus accelerating the aging process. In order to carry out a burn-intest, the modules are arranged within a test apparatus on a carriersubstrate, on which a plurality of connection locations are arranged. Anintegrated module is placed onto the respective connection location,with the result that the corresponding module may be connected, via aconnection location, to a test unit connected to the carrier substrate.

[0005] When carrying out a burn-in test of integrated modules such as,for example, DRAMs, a high level of parallelism is usually required inorder to achieve a high throughput. This results in the requirement thatmany modules are driven at the same time in order to achieve as high athroughput as possible in the case of a comparatively long burn-in testwhich may last for a plurality of hours. However, the disadvantage ofthis high level of parallelism is a resultant reduced edge steepness ofsignals of the modules to be tested and an associated lower possibleoperating frequency. Increased demands are furthermore imposed on thepower supply of the carrier substrate, the burn-in board, where thepower supply is often being fully utilized and thus limiting the numberof modules per burn-in board. The disadvantages described are presentduring a functional test in which, although the modules are notstressed, they are, for reasons of test economy, located on the burn-inboard in order, for example, to be able to carry out a functional testat increased operating frequency using the high level of parallelism(test during burn-in).

[0006]FIG. 2 shows a test apparatus for testing integrated modulesaccording to the prior art. Such test apparatus can be used to achieve ahigh level of parallelism. A burn-in test unit 2 is connected to thecarrier substrate 10, on which a plurality of connection locations 11 tonk are arranged. The connection locations are designed such that anintegrated module DUT may be connected, via a respective connectionlocation, to the test unit 2 connected to the carrier substrate 10.Since a burn-in test unit generally has a limited number of inputs, theconnection locations 11 to nk are arranged in a matrix-type connectionarray. More modules to be tested than input channels (present on thetester side) are therefore located on the burn-in board.

[0007] For the purposes of driving the modules DUT, the connection arrayis divided into groups, the individual groups being read sequentiallyvia the control signals SCAN-1 to SCAN-n. This SCAN signal is connectedto the DQM pin on the module to be tested. The pin masking the outputdrivers of the modules, which, despite internal execution of commands inthe module, therefore, do not output any signals. Control signals, suchas addresses and commands, are fed simultaneously into all of themodules via the address and command bus CMD/ADD. The data are output bythe respective module at the data output DQ, depending on driving of theDQM signal, and the addresses and commands are read in via the addressand command terminal A/C.

[0008] In the test apparatus shown in FIG. 2, all or none of the modulesDUT will operate internally. The SCAN signal is accorded a function forreading out data in order to activate the output drivers of the desiredgroup of modules via the respective DQM pin. In particular, in a testduring burn-in (described above), the driver load on the address andcommand bus CMD/ADD is comparatively high as a result of the paralleloperation of the modules, with the result that the address and commandsignals are subject to a resultant reduced edge steepness. High demandsare furthermore imposed on the power supply of the burn-in board duringtests of this type.

SUMMARY

[0009] A test apparatus for testing integrated modules may be used tooperate the modules at increased frequency in a functional test or maybe used, for the same load, to increase the number of modules, which canbe arranged on the carrier substrate.

[0010] Also, a corresponding method for operating a test apparatus ofthis type is possible.

[0011] In the test apparatus according to the invention, the connectionlocations can be arranged in groups within a connection array. A dataterminal can be provided for each connection location. The dataterminals of connection locations of a respective group can be connectedto a respective different data bus. A control terminal, via which anintegrated module may be selected for a test, can be provided for eachconnection location. The control terminals of connection locations of arespective group can be connected to a control bus assigned to thisgroup. An address and command terminal can be provided for eachconnection location. It is possible for the address and commandterminals of connection locations of a respective group to be connectedto an address and command bus via a switching means, which is assignedto the respective group and may be controlled by the control busassigned to this group.

[0012] The test apparatus according to the invention for testingintegrated modules can make it possible to operate the modules at ahigher frequency in a functional test since individual groups ofconnection locations may be selected via the control bus and modules ofselected groups can be correspondingly selected for a test. Also, theselected connection locations can be connected to the address andcommand bus via the switching means, which is driven by the respectivecontrol bus. As a result, the driver load on the address and command busof the test apparatus can decrease since address and command terminalsof modules of a selected group or of a plurality of selected groups areconnected to the address and command bus. At the same time, the demandsimposed on the power supply of the test apparatus can decrease sincemodules of selected groups are selected via the respective control bus,and consequently, the other modules, which have not been selected, areswitched off or are in a standby state. Thus, the effective load can bereduced or, for the same load, the number of modules, which can bearranged on the carrier substrate, can be increased.

[0013] In a corresponding operating method, at least some of theconnection locations on the carrier substrate can be connected tointegrated modules to be tested. Driving the corresponding controlbus(es) can simultaneously operate and drive modules of a number ofgroups. This number can be smaller than the number of groups present onthe carrier substrate. The modules of the number of groups, which aresimultaneously operated, can be connected to the address and command busvia the respective switching means or switch. In particular, modules,which interchange data via the assigned data bus, can be operated anddriven by address and command signals.

[0014] Functional tests, such as a test during burn-in, can be carriedout. The modules can be subject, with a high level of parallelism, to aburn-in test on a burn-in board and, in a subsequent functional test,can be operated at increased operating frequency using the testinfrastructure of the burn-in board.

BRIEF DESCRIPTION OF THE FIGURES

[0015] The invention is explained in more detail below with reference tothe figures, which are illustrated in the drawing, in which:

[0016]FIG. 1 shows an embodiment of a test apparatus in accordance withthe invention, and

[0017]FIG. 2 shows an embodiment of a test apparatus according to theprior art, as described above.

DETAILED DESCRIPTION

[0018]FIG. 1 shows an embodiment of a test apparatus according to theinvention for testing integrated modules. The test apparatus includes aplurality of connection locations 11 to nk arranged on a carriersubstrate 1, i.e., a burn-in board in the present case. The connectionlocations 11 to nk can be designed such that an integrated module DUTmay be connected, via a connection location, to a test unit 2 connectedto the carrier substrate 1. The connection locations 11 to nk can form aconnection array, which, in the present case, is constructed in the formof a matrix in columns S1 to Sk and rows R1 to Rn. In this case, theconnection locations can be arranged in groups within the connectionarray. The groups can be formed by the respective rows R1 to Rn.

[0019] A data terminal DQ can be provided for each connection location,the data terminals DQ of connection locations of a respective row beingconnected to a respective different data bus D1 to Dk. A controlterminal CS, via which an integrated module DUT may be selected for atest, can be provided for each connection location. The controlterminals CS of connection locations of a respective row R1 to Rn can beconnected to a control bus SCAN-1 to SCAN-n assigned to this row. Theaddress and command terminals A/C of connection locations of a row R1 toRn can be connected to a common address and command bus CMD/ADD via arespective switching means T1 to Tn. The switching means can becontrolled by the control bus SCAN-1 to SCAN-n assigned to the row. Dataterminals DQ of connection locations along a column S1 to Sk can beconnected to the data bus D1 to Dk to be assigned to this column. Forreasons of clarity, the terminals DQ, A/C, CS have been illustrated inFIG. 1 with reference to the connection location 11, the otherconnection locations 12 to nk having analogous terminals. The data busesD1 to Dk can have the bit width m, for example, m=4, and the address andcommand bus CMD/ADD can have the bit width a, for example, a=6.

[0020] In a method for operating a test apparatus as shown in FIG. 1, atleast some of the connection locations 11 to nk on the carrier substrate1 can be connected to integrated modules DUT, in particular, DRAMs, tobe tested. Driving one or more control buses simultaneously operatesmodules of a number of rows. This number can be smaller than the numberof rows present on the carrier substrate 1. By way of example, drivingthe control bus SCAN-1 can select the group R1, with the result that themodules of this row R1 are operated via the control input CS. Themodules DUT of this row R1, which are simultaneously operated, can beconnected to the address and command bus CMD/ADD via the switching meansT1.

[0021] The SCAN signals can be used to drive, via the switchingtransistors T1 to Tn. The addresses and commands of those modules, inthe group to be activated. In addition, the SCAN signal can be connectedto the CS terminal of the modules instead of, as previously and asillustrated in FIG. 2, to the DQM terminal. In accordance with the testarrangement shown in FIG. 1, DQM terminal may now be connected to a freecommand terminal of the test unit. The SCAN signal can select addressesand commands for the active modules, with the result that the load onthe corresponding drivers can be reduced. Selected modules at a higherfrequency, in particular, in a test during burn-in, or to increase thenumber of modules per burn-in board can be operated.

[0022] The modules, which have been deactivated via the CS signal, canbe in the deactivated state or in the power-down mode. In the case ofDRAMs, the data of the deactivated chips can be refreshed by a “selfrefresh,” which is carried out automatically by the chip. With anincreasing number of deactivated chips, a reduced power consumption canresult. If a chip has been deactivated via the CS signal, the chip doesnot drive any data via the DQ terminal, does not receive any data viathe DQ terminal, and does not identify any commands at the terminal A/C.

[0023] In one embodiment of the invention, the modules which are locatedon the carrier substrate can be subject, during the method, to afunctional test at increased operating frequency, and beforehand and/orafterward to a burn-in test (which is different from the functionaltest) on the same carrier substrate, in the burn-in test, the modulesbeing operated at, in comparison, a lower operating frequency.Comparatively slow burn-in tests can be carried out by driving aplurality of or all SCAN signals using an operating current or driverload which can nevertheless be handled by the test system and with ahigh level of parallelism. However, the current-critical and,respectively, frequency-critical tests of modules, which are carried outon the same carrier substrate, can be carried out with a reduced levelof parallelism in accordance with the method according to the invention,with the result that the test frequency can be increased withoutadversely affecting the driver load. The test system is no longerrestricted by the power consumption which can be handled during a testduring burn-in, with the result that it is possible to increase thenumber of modules which are simultaneously subjected to a burn-in teston the test board.

[0024] While the invention has been described in detail and withreference to specific embodiments thereof, it will be apparent to oneskilled in the art that various changes and modifications can be madetherein without departing from the spirit and scope thereof.Accordingly, it is intended that the present invention covers themodifications and variations of this invention provided they come withinthe scope of the appended claims and their equivalents.

List of Reference Symbols

[0025]1 Carrier substrate

[0026]2 Test unit

[0027]10 Carrier substrate

[0028]11 to nk Connection location

[0029] DUT Integrated module

[0030] T1 to Tn Switching means

[0031] D1 to Dk Data bus

[0032] SCAN-1 to SCAN-n Control bus

[0033] CMD/ADD Address and command bus

[0034] A/C Address and command terminal

[0035] DQ Data terminal

[0036] CS Control terminal

[0037] R1 to Rn Row

[0038] S1 to Sk Column

[0039] m, a Bit width

We claim:
 1. A test apparatus for testing integrated modules, comprisinga carrier substrate, the carrier substrate having a plurality ofconnection locations are arranged thereon, the connection locationsbeing designed such that an integrated module is connected to a testunit connected to the carrier substrate via a connection location, theconnection locations forming a connection array, the connectionlocations being arranged in groups within the connection array; a dataterminal provided for each connection location, the data terminals ofconnection locations of a respective group being connected to arespective different data bus; a control terminal provided for eachconnection location, the control terminal selecting the integratedmodule for a test, the control terminals of connection locations of arespective group being connected to a control bus assigned to thisgroup; and an address and command terminal provided for each connectionlocation, the address and command terminals of connection locations of arespective group being connected to an address and command bus via arespective switching means, which is assigned to the respective groupand controlled by the control bus assigned to this group.
 2. The testapparatus as claimed in claim 1, wherein the connection locations arearranged in rows and columns within the connection array, the dataterminals of connection locations of a respective column are connectedto a data bus assigned to this column, the control terminals ofconnection locations of a respective row are connected to a control busassigned to this row, and the address and command terminals ofconnection locations of a respective row are connected to a commonaddress and command bus via a respective switching means, which may becontrolled by the control bus assigned to this row.
 3. The testapparatus as claimed in claim 1, wherein the carrier substrate is in theform of a burn-in test board.
 4. A method for operating a testapparatus, the test apparatus including at least some connectionlocations on the carrier substrate being connected to integrated modulesto be tested, the method comprising: driving corresponding controlbus(es) to simultaneously operate and drive modules of a number ofgroups of connection locations, wherein the number is less than thenumber of groups present on the carrier substrate; and in simultaneouslyoperating the modules of the number of groups, the groups beingconnected to the address and command bus via the respective switchingmeans.
 5. The method as claimed in claim 4, wherein the connectionlocations are arranged in rows and columns within the connection arrayand the modules of a number of rows are simultaneously operated anddriven, the number being smaller than the number of rows present on thecarrier substrate, and the modules of the number of rows which aresimultaneously operated are connected to the address and command bus viathe respective switching means.
 6. The method as claimed in claim 4,wherein the modules which interchange data via the assigned data bus areoperated and driven.
 7. The method as claimed in claim 4, wherein themodules are subject to a functional test and beforehand and/or afterwardto a burn-in test on the same carrier substrate.
 8. The method asclaimed in claim 7, wherein the modules are operated at a firstoperating frequency in the burn-in test and at a second operatingfrequency in the functional test, the first operating frequency beingsmaller than the second operating frequency.
 9. The method as claimed inclaim 7, wherein, during a burn-in test, driving the correspondingcontrol buses simultaneously operates the modules of all groups, and themodules of the groups are connected to the address and command bus viathe respective switching means.
 10. A test apparatus for testingintegrated modules, comprising a carrier substrate, the carriersubstrate having a plurality of connection locations are arrangedthereon, the connection locations being designed such that an integratedmodule is connected to a test unit connected to the carrier substratevia a connection location, the connection locations forming a connectionarray, the connection locations being arranged in groups within theconnection array; a data terminal provided for each connection location,the data terminals of connection locations of a respective group beingconnected to a respective different data bus; a control terminalprovided for each connection location, the control terminal selectingthe integrated module for a test, the control terminals of connectionlocations of a respective group being connected to a control busassigned to this group; and an address and command terminal provided foreach connection location, the address and command terminals ofconnection locations of a respective group being connected to an addressand command bus via a respective switch, which is assigned to therespective group and controlled by the control bus assigned to thisgroup.
 11. The test apparatus as claimed in claim 10, wherein theconnection locations are arranged in rows and columns within theconnection array, the data terminals of connection locations of arespective column are connected to a data bus assigned to this column,the control terminals of connection locations of a respective row areconnected to a control bus assigned to this row, and the address andcommand terminals of connection locations of a respective row areconnected to a common address and command bus via a respective switch,which may be controlled by the control bus assigned to this row.
 12. Thetest apparatus as claimed in claim 10, wherein the carrier substrate isin the form of a burn-in test board.
 13. A method for operating a testapparatus, the test apparatus including at least some connectionlocations on the carrier substrate being connected to integrated modulesto be tested, the method comprising: driving corresponding controlbus(es) to simultaneously operate and drive modules of a number ofgroups of connection locations, wherein the number is less than thenumber of groups present on the carrier substrate; and in simultaneouslyoperating the modules of the number of groups, the groups beingconnected to the address and command bus via the respective switch. 14.The method as claimed in claim 13, wherein the connection locations arearranged in rows and columns within the connection array and the modulesof a number of rows are simultaneously operated and driven, the numberbeing smaller than the number of rows present on the carrier substrate,and the modules of the number of rows which are simultaneously operatedare connected to the address and command bus via the respective switch.15. The method as claimed in claim 13, wherein the modules whichinterchange data via the assigned data bus are operated and driven. 16.The method as claimed in claim 13, wherein the modules are subjected toa functional test and beforehand and/or afterward to a burn-in test onthe same carrier substrate.
 17. The method as claimed in claim 16,wherein the modules are operated at a first operating frequency in theburn-in test and at a second operating frequency in the functional test,the first operating frequency being smaller than the second operatingfrequency.
 18. The method as claimed in claim 16, wherein during aburn-in test, driving the corresponding control buses simultaneouslyoperates the modules of all groups, and the modules of the groups areconnected to the address and command bus via the respective switch.